function MyFunction() {
    x = document.getElementById("demo");
    x.innerHTML = "hello js";
}
function test() {
    x = document.getElementById("demo");
    x.style.color = "#22ffff";
}
function alertDialog() {
    alert("My first js");
}
function testVar() {
    var x = 2;
    var y = 3;
    var z = x+y;
    var pi = 3.14;

    // document.write(z + "<br>");

    var y = 123.12;
    var t = z + pi + y;
    var tt = true;
    var cars = new Array();
    cars[0] = "Audi";
    cars[1] = "BMW";
    cars[2] = "Volvo";
    var carsss;
    var personsss = null;
    var carname = new String("sss");
    var xxxx = new Boolean(true);
    var carssss = new Array();

    carname = "shiweiwei";
    //对象属性
    var person={
        firstname:"Bill",
        lastname:"Gates",
        id:5566
    };
    for (var i = 0; i < cars.length; i++){
        carsss += cars[i] + "<br>";

    }
    carsss += person.firstname +"<br>";
    carsss += carname;
    document.getElementById("my_var").innerHTML = carsss;

}
function testInner() {

    document.getElementById("demo").innerHTML = "Hello world";
    document.getElementById("myDiv").innerHTML="how are you";
    document.write("这是一个 \ 测试");
}
